Via configuration for differential signaling through power or ground planes

Abstract

A circuit board including a conductive plane, a first via and a second via. The first and second vias extend through the conductive plane such that there is no conductive material between the first and second vias within the conductive plane.

What is claimed:  
     
         1 . A circuit board comprising: 
 a first conductive plane;    a first via extending through the first conductive plane; and    a second via extending through the first conductive plane, wherein there is no conductive material between the first and second vias within the first conductive plane.    
     
     
         2 . The circuit board of  claim 1  wherein each via carries a component of a digital differential signal.  
     
     
         3 . The circuit board of  claim 2  wherein the digital differential signal has a transition rate of at least 10 giga transitions per second.  
     
     
         4 . The circuit board of  claim 1  wherein there is an insulating material between the first and second vias in the first conductive plane.  
     
     
         5 . The circuit board of  claim 1  wherein there is no material between the first and second vias in the first conductive plane.  
     
     
         6 . The circuit board of  claim 1  further comprising traces electrically coupled to the first via and the second via.  
     
     
         7 . The circuit board of  claim 1  wherein the first and second vias are copper.  
     
     
         8 . The circuit board of  claim 1  further comprising a second conductive plane, the first and second vias extending through the second conductive plane such that there is no conductive material between the first and second vias in the second conductive plane.  
     
     
         9 . The circuit board of  claim 8  further comprising an insulating layer between the first and second conductive planes.  
     
     
         10 . The circuit board of  claim 8  wherein the first and second conductive planes are copper.  
     
     
         11 . The circuit board of  claim 8  wherein the first and second conductive planes are substantially parallel.  
     
     
         12 . The circuit board of  claim 11  wherein the first and second vias are substantially parallel as the first and second vias extend through the first and second conductive planes.  
     
     
         13 . The circuit board of  claim 12  wherein the first and second vias extend orthogonally through the first and second conductive planes.  
     
     
         14 . The circuit board of  claim 8  wherein the first conductive plane is a power plane and the second conductive plane is a ground plane.  
     
     
         15 . A computer system comprising: 
 a bus;    a memory coupled to the bus; and    a circuit board electrically coupled to the bus, the circuit board including a first conductive plane and first and second vias extending through the first conductive plane with no conductive material between the first and second vias within the first conductive plane.    
     
     
         16 . The computer system of  claim 15  further comprising a second conductive plane, the first and second vias extending through the second conductive plane with no conductive material between the first and second vias within the second conductive plane.  
     
     
         17 . The computer system of  claim 16  wherein the first conductive plane is a power plane and the second conductive plane is a ground plane.  
     
     
         18 . A circuit board comprising: 
 a power plane;    a ground plane;    a first via extending through the power and ground planes;    a second via extending through the power and ground planes, wherein there is no conductive material between the first and second vias within the power plane and the ground plane, the first and second vias being substantially parallel to one another as the first and second vias extend orthogonally through the power and ground planes; and    traces electrically coupled to the first via and the second via.    
     
     
         19 . The circuit board of  claim 18  wherein each via carries a component of a digital differential signal.  
     
     
         20 . The circuit board of  claim 19  further comprising an insulating layer between the power plane and the ground plane.